Electric projection device



Feb. 13, 1940. D. K. WRIGHT ELECTRIC PROJECTION DEVICE Original Filed March 15, 1936 h .3 s rm 8 o n K t W12 .m

Patented Feb. 13, 1940 PATENT OFFICE v ELECTRIC rao'mc'rrofw nnvrca Daniel K. Wright, Cleveland Heights, out, assignor to General Electric Company, a corporation of New York 2 Application March 13,1936, Serial a... 68,714 Renewed May 21, 1837 1 Claims. f(c1. 110-44 My invention relates to light projecting devices comprising'an enclosure or bulb, .a portion of which is reflective of light. My invention may be applied to light projecting devices in which the light source is fixed at aldeflnite point, such as the focal point of a reflector or other device for projecting the light. More particularly my invention may be applied to light projecting devices of the type in which a portion or section of the enclosure for the light source has a concave light concentrating surface, such as a paraboloid, at the focus of which is located the filament or other light source. One of the advantages of such light projectors is that they may be made in small sizes for use as headlamps on vehicles such as automobiles and airplanes where the small-sized projector may be eflectively incorporated in the stream lined design of the vehicle. Another advantage is the possibility of extremely accurate location of the light source with respect to the reflecting surface whereby a beam of the desired dimensions and direction may always be secured.

According to my invention the light projector comprises a concave metal reflector having a cover glass or lens'sealed across the front thereof,

tages of my invention will appear from the following detailed description of a species thereof and from the drawing.

The drawing is an elevation in section of a light projecting device comprising my invention.

Referring to the drawing, the projector comprises a concave metal reflector i0, preferably of paraboloidal shape, and having the inner surface ll thereof silvered. A cylindrical metal base shell i2 has a flange portion II which is united,

preferably by welding, to the rim of an opening at the apex of the reflector 10. A metal exhaust tube l4 extends through the base shell l2 and is sealed therein by a plastic insulating material ll, preferably glass. With a glass seal ii, the tube It and shell' i2 may be made of an alloy known as Femico and described in Patent No. 1,942,280,,

issued January 2, 1984 to Howard Scott, or of a chrome-iron alloy known as Allegheny 55, de-

pending upon whether a hard or soft glass is used. A filament It is mounted on lead wires I1, I 8 which may be spot welded to the reflector i0 and the exhaust tube It respectively. The filament I8 is located accurately-with respect to the focus 5 of the reflector ill. The said filament It may be located definitely by means of a suitable jig and then optically by placing the unit in a bottle containing a hydrogen or other non-oxidizing atmosphere, connecting the shell I2 and tube l4 10 to a source of electrical current to energize the filament, and observing the beam produced thereby on a screen. If the filament is not correctly located, an operator may reach into the bottle and slightly bend the leads l1, I! to adjust the 15 position of the filament. The filament is also located angularly with respect to outward projections such as pins I! on the base shell i2.

The front of the reflector Iii is covered by a cover glass 20 which may be a plain glass, but go for vehicle headlamp purposes is preferably a lens of suitable design having flutes and prisms to properly distribute the light. A ring 2i of metal or alloy such as Fernlco or Allegheny 55 is sealed by fusion directly to the rim of the cover glass 25 20 and has an outwardly extending flange por- .tion 22 which is in turn united, preferably by welding, to an outwardly extending flange 23 at the rim of the reflector ill, or to an annular protuberance 24 thereon. In this way, the silver or other reflecting coating onthe inner surface I i of the reflector is not harmed and a hermetical seal is obtained.

After the parts have been assembled, the enclosure Ill, 20 is evacuated and may be fllled with an inertgas through the exhaust tube H which is then sealed oil as shown in the drawing and servesas one of the terminals for conducting I current to the filament it.

What I claim as new and desire to secure by 40 Letters Patent of the United States is:

l. A light projecting device comprising a concave metal reflector, a cover glass, 9, metal ring sealed directly-to the rim of said cover glass and united to the rim of said reflector to form 45 ahermetically sealed enclosure, and a light source mounted in said enclosure in deflnite relation to the focus of said reflector.

2. A light projecting device comprising a concave metal reflector having an outwardly ex- 50 tending flange at the rim thereof, a cover glass,

a metal ring sealed directly to the rim of said cover glass and having an outwardly extending flange portion united to the-flange on said reflector to form a hermetically sealed enclosure, 5

and a light source mounted in said enclosure in deflnite relation to the focus of said reflector.

3. A light projecting device comprising a concave metal reflector, a cover glass sealed over the front of said reflector to form a hermetically sealed enclosure, a metal exhaust tube sealed in an opening at the back of said reflector and insulated therefrom, a light source in said nclosure located in definite relation to the i us oi. said reflector, and a pair of leads supporting said light source, one of said leads being secured to said reflector and the other to said metal exhaust tube.

4. In a light-projecting device, the combination of a hermetically sealed enclosure containing a light source, said enclosure comprising a metal portion at least part of which is shaped to constitute a concave reflector, another portion of 'said enclosure being a glass cover, said glass cover being fused at its periphery directly to a part of the metal portion of said enclosure to form a hermetical seal.

5. In a light-projecting device, the combination of a hermetically sealed enclosure containing a light source, said enclosure comprising a metal portion at least part of which is shaped to constitute a concave reflector, another portion of said enclosure being a glass cover, said glass cover being fused at its periphery directly to a -metal portion at least part of which is shaped to constitute a concave reflector, another portion of said enclosure being a glass cover, said glass cover being fused at its periphery directly to a part of the metal portion of said enclosure to form a hermetical seal, said reflector portion of said enclosure having a metal exhaust tube sealed I in an opening at its apex.

7. In a light-projecting device, the combination of a hermetically sealed enclosure comprising a metal portion at least part of which is shaped to constitute a comparatively deep concave reflector, another portion of said enclosure being a glass cover, said glass cover being fused at its periphery directly to a part of the metal portion of said enclosure to form a hermetlcal seal, and a light source sealed in said enclosure and positioned intermediate the bottom and the rim of said reflector portion in accurate relation with respect to the surface of said reflector portion.

, DANIEL K. WRIGHT. 

